Single-stage or multi-stage radial-flow scrubbers or coolers are known, e.g., from German Patent Specification 1,241,804; 2,546,674; 1,259,361; and 2,224,519. It is known to adjust the gas flow gap of these scrubbers by lifting means, which are preferably driven by electric motors and actuated by mechanical transmissions. The lifting means are accommodated in a separate chamber or tunnel and actuate the adjustable member by means of a linkage. Hydraulic or pneumatic actuators are also known for this purpose and mechanical linkages comprising levers or eccentrics have also been used.
All these designs have the disadvantage that the movable structured elements, such as shafts, rods, levers, pistons, push rods, etc. which perform an axial or rotary motion, must be sealed against the supply pressure or against the differential pressure in the scrubber. Because these scrubbers are used to scrub solid or gaseous impurities from gases, the impurities result in a formation of crusts (e.g. of lime) or caked-on layers (e.g. of ask or salts) or bonding layers (e.g. of tar) so that the seals required for the known lifting means are destroyed rapidly and the scrubber must be repaired.
In numerous applications, seals of soft materials, such as rubber or teflon, cannot be used because they are destroyed by aggressive fluids. Specifically, the known scrubbers cannot be operated in a sufficiently troublefree manner behind apparatus which serves for the gasification of coal under pressure and delivers product gases which contain tars, dust, and aggressive fluids.